Patchwork [14/31] block: Clean up bdrv_flush_all()

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Submitter Kevin Wolf
Date Sept. 6, 2011, 3:39 p.m.
Message ID <1315323586-23840-15-git-send-email-kwolf@redhat.com>
Download mbox | patch
Permalink /patch/113627/
State New
Headers show

Comments

Kevin Wolf - Sept. 6, 2011, 3:39 p.m.
From: Markus Armbruster <armbru@redhat.com>

Change (!bdrv_is_removable(bs) || bdrv_is_inserted(bs)) to just
bdrv_is_inserted().  Rationale:

    The value of bdrv_is_removable(bs) matters only when
    bdrv_is_inserted(bs) is false.

    bdrv_is_inserted(bs) is true when bs is open (bs->drv != NULL) and
    not an empty host drive (CD-ROM or floppy).

    Therefore, bdrv_is_removable(bs) matters only when:

    1. bs is not open
       old: may call bdrv_flush(bs), which does nothing
       new: won't call

    2. bs is an empty host drive
       old: may call bdrv_flush(bs), which calls driver method
            raw_flush(), which calls fdatasync() or equivalent, which
            can't do anything useful while the drive is empty
       new: won't call

Result is bs->drv && !bdrv_is_read_only(bs) && bdrv_is_inserted(bs).
bdrv_is_inserted(bs) implies bs->drv.  Drop the redundant test.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

Patch

diff --git a/block.c b/block.c
index 2158f83..487a6a9 100644
--- a/block.c
+++ b/block.c
@@ -1753,8 +1753,7 @@  void bdrv_flush_all(void)
     BlockDriverState *bs;
 
     QTAILQ_FOREACH(bs, &bdrv_states, list) {
-        if (bs->drv && !bdrv_is_read_only(bs) &&
-            (!bdrv_is_removable(bs) || bdrv_is_inserted(bs))) {
+        if (!bdrv_is_read_only(bs) && bdrv_is_inserted(bs)) {
             bdrv_flush(bs);
         }
     }